US5604723A - Method for reading a synchronizing signal from a record medium and an apparatus thereof - Google Patents

Method for reading a synchronizing signal from a record medium and an apparatus thereof Download PDF

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US5604723A
US5604723A US07/642,575 US64257591A US5604723A US 5604723 A US5604723 A US 5604723A US 64257591 A US64257591 A US 64257591A US 5604723 A US5604723 A US 5604723A
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count value
data
time period
synchronizing pattern
counter
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Kazuyoshi Kikuta
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Fujitsu VLSI Ltd
Fujitsu Ltd
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Fujitsu VLSI Ltd
Fujitsu Ltd
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/12—Formatting, e.g. arrangement of data block or words on the record carriers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/14—Digital recording or reproducing using self-clocking codes
    • G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
    • G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
    • G11B27/30—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording
    • G11B27/3027—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording used signal is digitally coded
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • G11B7/013—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track for discrete information, i.e. where each information unit is stored in a distinct discrete location, e.g. digital information formats within a data block or sector
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/14—Digital recording or reproducing using self-clocking codes
    • G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
    • G11B2020/1476—Synchronisation patterns; Coping with defects thereof
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/20—Disc-shaped record carriers
    • G11B2220/21—Disc-shaped record carriers characterised in that the disc is of read-only, rewritable, or recordable type
    • G11B2220/215—Recordable discs
    • G11B2220/218—Write-once discs

Definitions

  • the present invention relates generally to a method and an apparatus for reading out a synchronizing signal from a recording medium and, more particularly, is directed to a method and an apparatus for reading out a synchronizing signal provided in a data portion of each sector stored in a recording medium such as an optical disc, a read only type optical disc or a write-in-once (WIO) type optical disc, a magneto-optical disc.
  • a recording medium such as an optical disc, a read only type optical disc or a write-in-once (WIO) type optical disc, a magneto-optical disc.
  • each sector on the optical disc is composed of an ID portion 10 and a data portion 11, as shown in FIG. 1.
  • the data portion 11 comprises of a sync. data portion (SYNC) 11a at its head, a number of divided data portions 11b composed of 15 bytes or 20 bytes are formed and a re-sync. data portion (RESYNC) 11c is formed between the divided data portions 11b.
  • Data recorded in the data portion 11 is recorded in a distributed manner in the respective divided data portions 11b.
  • Sync. pattern data which becomes a sync. signal is recorded on the sync. pattern data portion 11a and re-sync. pattern data which becomes a re-sync. signal is recorded on the re-sync.
  • data in the starting divided data portion 11b is read out on the basis of the data (sync. signal) in the sync. data portion 11a and data in the succeeding divided data portion 11b is read out on the basis of data (re-sync. signal) in the re-sync. data portion 11c. That is, data in the respective divided data portions 11b are read out at the detection timings of the sync. signal and the re-sync. signal.
  • the sync. signal or the re-sync. signal must be detected within its detection period. Then, detection starting and ending timings of the limited detection period of the succeeding re-sync. signal are determined by the detection of the sync. signal. Thus, if the sync. signal cannot be detected, the succeeding re-sync. signal cannot be detected. There is then the substantial disadvantage that data cannot be read out from the optical disc at all.
  • the recording density of the optical disc is 1 bit/ ⁇ m 2 which is more than one digit bigger comparing with magnetic disc or magnetic tape, it is apt to be affected by micro fault and many bit errors are apt to occur.
  • the bit error rate is about 10 -5 (one reading error per 10 5 bits) which is 4 to 5 digits larger comparing with recording media such as magnetic disc. Therefore, in particularly, in an optical disc in which a read error occurs more frequently than with other recording media, frequent occurrence of such read errors of the sync. signal becomes a serious problem.
  • data recording in the optical disc is performed such that the data (composed of user data and a control word) is divided into bits or word units and then is recorded by changing their orders. This is called interleave and by adapting this method burst errors are changed into random errors or short word errors, thereby the correcting capacity being increased.
  • an error check code called CRC (Cyclic Redundancy Check) or CRCC (Cyclic Redundancy Check Code) is formed in each one sector from data row of each interleave, then an error check code (ECC) composed of Read Solomon product code or Read Solomon Long Distance Code are generated based on above data and above CRC in each interleave.
  • ECC error check code
  • An object of the present invention is to provide a method and apparatus for reading out a sync. signal from a recording medium in which, even if the detection of the sync. signal fails, the succeeding re-sync. signal can be detected positively so that data following the first re-sync. signal can be read out reliably regardless of a drop-out of a first divided portion of data.
  • Another object of the present invention is to provide a method and apparatus for reading out a sync. signal from a recording medium in which the data-read error rate can be reduced.
  • a method for reading a synchronizing signal from a recording medium in which, when synchronizing data is detected from the recording medium in which a number of sectors, each sector being composed of an address portion and a data portion having synchronizing pattern data at its head, the data portion being divided into a plurality of divided data portions and re-synchronizing pattern data being formed between the divided data portions, re-synchronizing pattern data to be detected next is detected within a predetermined detection period.
  • This method is characterized in that, when detection of the synchronizing pattern data fails, the detection period of the re-synchronizing pattern data is prolonged to detect re-synchronizing pattern data.
  • a method for reading a synchronizing signal from a recording medium in which, when synchronizing data is detected from the recording medium in which a number of sectors, each composed of an address portion and a data portion having synchronizing pattern data at its head, the data portion being divided into a plurality of divided data portions and re-synchronizing pattern data being formed between the divided data portion, re-synchronizing pattern data to be detection period
  • the method for reading a synchronizing signal from a record medium is characterized in that, when the detection of the synchronizing pattern data has failed, the detection period of the re-synchronizing pattern data is prolonged to detect re-synchronizing pattern data.
  • the apparatus for reading a synchronizing signal from the record medium according to the present invention is provided with the following means.
  • a synchronizing pattern detecting means is adapted to detect synchronizing pattern data provided at the head of a data portion read out from the record medium in which a number of sectors, each sector being composed of an address portion and a data portion having synchronizing pattern data at the head thereof, the data portion being divided into a plurality of divided data portions and re-synchronizing pattern data being formed between the divided data portions.
  • a re-synchronizing pattern detecting means is adapted to detect the re-synchronizing pattern data formed between the divided data portions read out from the recording medium.
  • a synchronizing pattern detecting and judging means is adapted to determine whether or not the synchronizing pattern data is detected successfully by the synchronizing pattern detecting means.
  • a re-synchronizing pattern detecting and judging means is adapted to determine within a pre-determined detecting and judging period whether or not the re-synchronizing pattern data is detected successfully by the re-synchronizing pattern detecting means.
  • a control means is adapted to prolong the detecting and judging period of the re-synchronizing pattern detecting and judging means on the basis of the judged result of the synchronizing pattern detecting and judging means when the synchronizing pattern detecting and judging means determines that the detection of the synchronizing pattern data by the synchronizing pattern detecting means has failed.
  • the detecting period of the re-sync. pattern data is prolonged to thereby detect the re-sync. pattern data.
  • the duration of the detecting period of the re-sync. pattern data to be detected next is prolonged compared with the case where the detection of the sync. pattern data is successful, a probability that the re-sync. pattern data is detected is increased.
  • the sync. pattern detecting and judging means determines that the sync. pattern detecting means has failed in detecting the synchronizing pattern data.
  • the control means controls the re-sync. pattern detecting and judging means on the basis of the judged result of this detection failure such that the duration of the detecting and judging period of the re-sync. pattern detecting and judging means is longer than the case where the re-sync. pattern detecting and judging means successfully detects the re-sync. pattern data.
  • FIG. 1 is a schematic diagram showing the format of each sector in an optical disc
  • FIG. 2 is a circuit block diagram of a sync. signal reading apparatus which embodies the present invention
  • FIG. 3 shows one structure of the first, second and third control circuit
  • FIG. 4 shows another structure of the second control circuit
  • FIG. 5 shows a structure of a compound circuit of the first and the third control circuit
  • FIG. 6 is a truth value table
  • FIG. 7 is a timing chart of various signals used in the present invention, and to which references will be made in explaining a case where sync. pattern data is detected successfully;
  • FIG. 8 is a timing chart of various signals used in the present invention, and to which references will be made in explaining a case where the detection of sync. pattern data fails.
  • a shift register 21, a sync. pattern memory 22 and a comparator 23 constitute a sync. pattern detecting and a sync. pattern detection judging means.
  • the shift register 21 is adapted to 48 bits of shift data one bit at a time each time data recorded and read out from an optical disc by a recording and reproducing optical head (not shown) is output one bit at a time from a signal processing circuit, not shown and to store therein a total of 48 bits of data. Accordingly, the shift register 21 stores the latest 48 bits of data.
  • the sync. pattern memory 22 is formed of a read only memory (ROM) and stores the same sync. pattern data as the sync. pattern data recorded in a sync. data portion 11a shown in FIG. 1, that is, the sync. pattern data comprising 48 bits of data.
  • ROM read only memory
  • the comparator (digital comparator) 23 compares the latest 48 bits of data read from the optical disc stored in the shift register 21 with the 48 bits of sync. pattern data stored in the sync. signal pattern memory 22 to thereby detect whether or not the sync. pattern data is involved in the data sequentially read out from the optical disc.
  • a detection time of the comparator 23 for comparing and detecting the above described two data is controlled on the basis of an enable signal EN1 which will be referred to later. If it is determined during the detection time that the sync. pattern data is included in the data sequentially read out from the optical disc, that is, the latest 48 bits of data stored in the shift register 21, the comparator 23 outputs a sync. signal detecting signal SG1 (the pulse of the logic [H]), as shown in FIG. 7.
  • a shift register 24, a re-sync. signal pattern memory 25 and a comparator (digital comparator) 26 constitute a re-sync. pattern detecting means and non-synchronizing pattern detection judging means.
  • the shift register 24 shifts data one bit at a time each time 16 bits of data recorded and read out from the optical disc by means of the recording and reproducing head (optical head) as described above is output one bit at a time from a signal processing circuit, not shown and stores a total of 16 bits of data of totally 16 bits. Accordingly, the shift register 24 stores the latest 16 bits of data read from the optical disc.
  • the re-sync. signal pattern memory 25 is a read only memory (ROM) and stores the same re-sync. pattern data as the re-sync. pattern data recorded in a re-sync. data portion 11c shown in FIG. 1, that is, the 16 bits of re-sync. pattern data.
  • ROM read only memory
  • Comparator 26 compares 16 bits of data stored in the shift register 24 and the re-sync. pattern data stored in 16 bits of the re-sync. signal pattern memory 25 to thereby detect whether or not the re-sync. pattern data is included in the data sequentially read out from the optical disc.
  • a detection time for detecting the non-synchronizing pattern data of the comparator 26 is controlled on the basis of an enable signal EN2 which will be referred to later, and the comparator 26 outputs a re-sync. signal detecting signal SG2 (the pulse of the logical [H]) as shown in FIG. 7, if it is determined during the detection time that the re-sync. pattern data is included in the shift register 24.
  • a reference clock counter 27 is an up-counter for performing a counting in synchronization with reference clock RFCLK generated from an external clock generator, not shown is reset and restarts the count operation each time a detecting means (not shown), for detecting data (VFO) recorded at the head of an ID portion of each sector outputs a detecting signal IDTOP.
  • the count value of the reference clock counter 27 is supplied to a first control circuit 28.
  • the first control circuit 28 outputs a set trigger signal (logic [H]) when the count value of the reference clock counter 27 reaches a pre-determined first value (hereinafter referred to as a sync. pattern detection starting time), whereas the first control circuit 28 outputs a reset trigger signal (logic [H]) when the count value of the reference clock counter 27 becomes a predetermined second value (referred to hereinafter as a sync. pattern detection ending time) which is larger than the sync. pattern detection starting time.
  • a set trigger signal logic [H]
  • a reset trigger signal logic [H]
  • the sync. pattern detection starting time and the sync. pattern detection ending time are values that are theoretically or experimentally obtained beforehand, and a time of highest probability in which the sync. pattern is stored in the shift register 21 and compared with the sync. signal pattern stored in sync. signal pattern memory 22 by comparator 23 is set within these times.
  • a first flip-flop circuit (hereinafter simply referred to as a first FF circuit) 29 responds to the above-mentioned set trigger signal output from the first control circuit 28 to output the enable signal EN1 to the comparator 23. It also responds to the reset trigger signal to erase the enable signal EN1 so that, while the FF circuit 29 outputs the enable signal EN1, or while the control circuit 28 outputs the reset trigger signal after the set trigger signal is outputted, the comparator 23 detects the presence or absence of the sync. pattern data and judges the detected result.
  • the set trigger signal from the first control circuit 28 is supplied to a second flip-flop circuit (hereinafter referred to as a second FF circuit) 30, and the reset trigger signal is output to an AND circuit 31.
  • a second flip-flop circuit hereinafter referred to as a second FF circuit
  • the second FF circuit 30 is supplied at a reset input terminal R with the sync. signal detection signal SG1 (logic [H]) from the comparator 23 and supplies the AND circuit 31 with a signal of logic [H] (high) level during the period in which the sync. signal detection signal SG1 is supplied thereto after the set trigger signal from the control circuit 28. Accordingly, when the comparator 23 cannot detect the sync. pattern during the period from the predetermined sync. pattern detection starting time to the sync. pattern detection ending time, the AND circuit 31 outputs the set trigger signal logic [H] to a succeeding third flip-flop circuit (hereinafter referred to as a third FF circuit) 32.
  • a third FF circuit a succeeding third flip-flop circuit
  • a re-sync. timing counter (hereinafter referred to as a timing counter) 33 is supplied with the sync. signal detection signal SG1 and the re-sync. signal detection signal SG2 from the comparators 23 and 26 and reset to start the count operation again in response to these signals.
  • a count value of the timing counter 33 is output to a second control circuit 34 and a latch signal thereof is output to an external apparatus (not shown).
  • the second control circuit 34 outputs a set trigger signal (logic [H]) to a set terminal S of the fourth flip-flop 35 later described when the count value of the timing counter 33 reaches a predetermined third value (hereinafter referred to as a first re-sync. pattern detection starting time), whereas the second control circuit 34 outputs a reset trigger signal (logic [H]) to a reset terminal R of the fourth flip-flop 35 when the count value of the timing counter 33 reaches a pre-determined fourth value (hereinafter referred to as a first re-sync. pattern detection ending time) that is larger than the re-sync. pattern detection starting time.
  • the re-sync. pattern detection starting time and the re-sync. pattern detection ending time are theoretically-or experimentally-obtained value, and a time of highest probability in which the re-sync. pattern data is stored in the shift register 24 and compared is set within these times after the sync. pattern data is detected.
  • a fourth flip-flop circuit (hereinafter referred to as a fourth FF circuit) 35 responds to the set trigger signal from the second control circuit 34 to output a signal of logic [H] (high) level to an AND circuit 36 and responds to the reset trigger signal to output a signal of logic [L] (low) level to the AND circuit 36.
  • the AND circuit 36 is supplied with a signal from the third FF circuit 32 through a NOT circuit 37. It outputs an enable signal EN2 of logic [H] level through an OR circuit 38 to the aforementioned comparator 26 while the fourth FF circuit 35 outputs the signal of logic [H] level when the signal of the third FF circuit 32 is maintained in its logic [L] level state.
  • the comparator 26 detects the presence or absence of a re-sync. pattern and judges the detected result while the period the reset signal is being output after the set trigger signal has been output from the second control circuit 34.
  • a third control circuit 39 is supplied with the count value from the reference clock counter 27 and outputs a set trigger signal when the count value reaches a pre-determined fifth value (hereinafter referred to as a second sync. pattern detection starting time) whereas the third control circuit 39 outputs a reset trigger signal when the input count value reaches a predetermined sixth value (hereinafter referred to as a second sync. pattern detection ending time).
  • the second re-sync. pattern detection starting time is preset to be ahead of the first re-sync. pattern detection starting time which is counted by the timing counter 33 when the comparator 23 detects the sync. pattern data.
  • the second re-sync. pattern detection ending time is set beforehand to be behind the first re-sync. pattern detection ending time which is counted by the timing counter 33 when the comparator 23 detects the sync. pattern data. Accordingly, the detection time (window) determined by the second re-sync. pattern detection starting time and the second re-sync. pattern detection ending time becomes longer than the detection time (window) determined by the first re-sync.
  • the second re-sync. pattern detection starting time is shorter than the first re-sync. pattern detection starting time and the second re-sync. pattern detection ending time is longer than the first re-sync. pattern detection ending time.
  • a fifth flip-flop circuit (hereinafter referred to as a fifth FF circuit) 40 responds to the set trigger signal of the third control circuit 39 to output a signal of logic [H] level to an AND circuit 41, and also responds to the reset trigger signal from the third control circuit 39 to output a signal of logic [L] level to the AND circuit 41.
  • the AND circuit 41 is supplied with a signal from the third FF circuit 32, and outputs an enable signal EN2 of logic [H] level through an OR circuit 38 to the comparator 26 while the fifth FF circuit 40 is outputting a signal of logic [H] level when the signal from the third FF circuit 32 is maintained in its logic [H] level state.
  • the comparator 23 does not output the sync. detection signal SG1 (logic [H]) when the sync. pattern data is not detected. Therefore, the second FF circuit 30 is not reset.
  • the set trigger signal (logic [H]) is output to the third FF circuit 32 from the AND circuit 31 and the output signal from the third FF circuit. 32 becomes logic [H]. In other words, when the sync.
  • the comparator 26 detects the presence or absence of the re-sync. pattern only while the third control circuit 39 is outputting the set trigger signal after the reset trigger signal.
  • the set trigger signal from the third control circuit 39 is output to a reset input terminal R of a sixth flip-flop circuit (hereinafter referred to as a sixth FF circuit) 42, and the reset trigger signal therefrom is output to the third FF circuit 32 and the AND circuit 45.
  • a sixth FF circuit a sixth flip-flop circuit
  • the sixth FF circuit 42 is supplied at its set input terminal with the re-sync. signal detection signal SG2 from the comparator 26.
  • the output from the FF circuit 42 is input to the AND circuit 45 through the NOT circuit (inverter) 44.
  • the reset trigger signal output from the third control circuit 39 is input to the other input terminal of the AND circuit 45.
  • the AND circuit 41 is closed and the AND circuit 37 is opened. Then the set trigger Signal and reset trigger signal output from the third control circuit 39 is not applied to the OR circuit 38. 0n the other hand, the set trigger signal and the reset trigger signal output from the second control circuit 34 is output to the comparator 26 through the 0R circuit 38. That is, the detection of the re-sync. pattern data is inhibited at a timing based on the third control circuit 39 until the next sector from now on and the re-sync. pattern data by the comparator 26 is detected by the comparator 26 at a timing controlled by the second control circuit 34.
  • FIG. 3 shows a first structural example of the first control circuit 28, the second control circuit 34 and the third control circuit.
  • the set timing register 62 stores the sync. pattern detection starting time (in case of the first control circuit 28), the first re-sync. pattern detection starting time (in case of the second control circuit 34) or the second re-sync. pattern detection starting time (in case of the third control circuit 39).
  • the reset timing register 62 stores the sync. pattern detection ending time (in case of the first control circuit 28), the first re-sync. pattern detection ending time (in case of the second control 39) or the second re-sync. pattern detection ending time (in case of the third control circuit 39).
  • the comparator 63 compares the sync. pattern detection starting time stored in the set timing register 61 and the count value output from the reference clock counter 27 and if they coincide, a set trigger signal is output to set terminal S of the first FF circuit 29.
  • the second control circuit 34 the first re-sync. pattern detection starting time and the count value of the timing counter 33
  • the third control circuit 39 the second re-sync. pattern detection starting time and the count value of reference clock counter 27 are compared and when they coincide, a set trigger signal is output to the set terminal S of the fourth FF circuit 35 and the set terminal S of the fifth FF circuit 40, respectively.
  • the comparator 64 compares the sync. pattern detection ending time stored in the reset timing register and the count value of the reference clock counter 27, and when they coincide the reset trigger signal is output to reset terminal R of the first FF circuit 29.
  • the second control circuit 34 the first re-sync. pattern detection ending time and the count value of the timing counter 33, and in case of the third control circuit 39, the second re-sync. pattern detection ending time and the reference clock counter 27 are respectively subjected to the comparison. When they coincide, the reset trigger signal is output to the reset terminal R of the fourth FF circuit 35 and the reset terminal R of the fifth FF circuit 40, respectively.
  • FIG. 4 shows the second structural example of the second control circuit 34.
  • the registers 101 and 102 are for storing the first re-sync. detection starting time and the first re-sync. detection ending time synchronizing with a down edge of the clock CLK.
  • Select terminal S in the selector 103 selectively outputs the data stored in the register 101 at logic [L] and the data stored in register 102 at logic [H].
  • the comparator 104 compares the selected data output from the selector 103 and the count value of the re-sync. timing counter 33 and when they coincide, a detecting signal d 1 with logic [H] is output to the clock terminal CK of the D-flip-flop 105.
  • the Q output of the D-FF 105 is a select signal supplied to a select terminal S of selector 103 and is a set trigger signal supplied to a set terminal S of the fourth FF circuit 35 shown in FIG. 2.
  • the D-FF 106 operates at a rising edge of the Q output of the D-FF 105 supplied to the clock terminal CK and the Q output is a reset trigger signal supplied to a reset terminal R of the fourth FF circuit 35 shown in FIG. 2.
  • the D-FFs 105 and 106 are reset every time the detecting signal IDTOP is detected, which is produced upon detecting the head of the ID portion 10 of the respective sectors.
  • the first re-sync. detection starting time and the first re-sync. pattern detection ending time are set in the registers 101 and 102, respectively, by an external control circuit, not shown.
  • the D-FF 105 and 106 are initially set to logic [L]. Therefore, the selector 103 outputs the first re-sync. pattern detection starting time stored in the register 101 to the comparator 104.
  • the comparator 104 compares the count value of the timing counter 33 with the first re-sync. pattern detection starting time and when the count value reaches the first re-sync. pattern detection starting time, detection signal d 1 of the logic [H] is output to the clock terminal CK of the D-FF 105.
  • the Q output of the D-FF 105 changes from logic [L] to logic [H] to provide a set trigger signal to be output to set terminal S of the fourth FF circuit 35, thereby changing set terminal S of the selector 103 from logic [L] to logic [H]. Therefore, the selector 103 outputs the first re-sync. pattern detection ending time stored in register 102 to the comparator 104.
  • the comparator 104 compares the first re-sync. pattern detection ending time with the count value of the timing counter 33.
  • detecting signal d 1 of logic [H] is again output. Therefore, the Q output of the D-FF 105 changes from logic [H] to logic [L], thereby enabling the set trigger signal to be in active.
  • the Q output of D-FF 105 changes from logic [L] to logic [H] and the Q output of the D-FF 106 changes from logic [L] to logic [H] and is applied to reset terminal R of the fourth FF circuit 35 at a reset trigger signal.
  • FIG. 5 a circuit obtained by combining the first control circuit 28 and the third control circuit 39 is shown in FIG. 5.
  • the memory 201 is an SRAM (Static Random Access Memory) and has the sync. pattern detection starting time, sync. pattern detection ending time, and second asynchronizing pattern detection starting time and second asynchronizing pattern ending time stored in addresses "0" to "3", respectively.
  • the memory 201 can perform a read/write when the chip select terminal CS is at logic [L]. When the output enable terminal of OE is at logic [L], CS is at logic [L], and write enable terminal WE is at logic [L], data is written. When write enable terminal WE is at logic [H], a data read out is performed. The address of the data read out is designated by read address signal input terminals A 0 and A 1 .
  • the comparator 202 compares the data read from the memory 201 with the count value of the reference clock counter 27 and when the data accords with the count value, the detecting signal d 2 of logic [H] is output to the clock terminal CK of the D-flip-flop (called D-FF hereinafter) 203.
  • the D-FF 203, 204 and 205 connected serially, comprise a binary counter and the Q output of the D-FFs 203 and 204 are read address signals A 0 and A 1 , respectively, of 2 bits of the memory 201.
  • the Q output of the D-FFs 203, 204 and 205 are applied to input terminals I 0 , I 1 and I 2 , respectively, of decoder 206.
  • the D-FFs 203, 204 and 205 are reset every time the detection signal IDTOP is output. This signal is produced when the head of ID portion 10 of respective sectors is detected.
  • the decoder 206 has a function displayed in a truth table shown in FIG. 6. It enables output terminals Y 0 , Y 1 , Y 2 , Y 3 to produce a set trigger signal to the set terminal S of the first FF circuit 29, a reset trigger signal to a reset terminal R of the first FF circuit 29, a set trigger signal to a set terminal S of the fifth FF circuit 35 and a reset trigger signal to a reset terminal R of the fifth FF circuit 35.
  • sync. pattern detection starting time, sync. pattern detection ending time, the second asynchronizing pattern detection starting time, and the second asynchronizing pattern detection ending time are written in the addresses "0" to "3" of the memory 201 by an external control circuit, not shown.
  • the read out of the optical disc starts through the record reproduction head and the data recorded at the head of the ID portion 10 of the sector is detected and when the detection signal IDTOP is output, the reference clock counter 27 is set and starts the count operation and the Q output of the D-FFs 203,204 and 205 are reset to logic [L].
  • the chip select terminal CS, the output enable terminal OE are set at logic [L] and write enable terminal WE are set at logic [L] by the control circuit, not shown, and the sync. pattern detection starting time is thus read out from address "0" of the memory 201 and output to the comparator 202.
  • a detection signal d 2 is output from the comparator 202 and the Q output of the D-FF 203 is set from logic [L] to logic [H]. Therefore, the input terminal I 0 of the decoder 206 turns to logic [H] and a set trigger signal is thus output from the output terminal Y 0 to the set terminal S of the first FF circuit 29.
  • the read address signal terminal A 0 of the memory 201 changes from logic [L] to logic [H] and the sync. pattern detection ending time is read from address "1" of the memory 201 and output to the comparator 202.
  • the detection signal d 2 is again output from the comparator 202. Therefore, the Q output of the D-FF 203 changes from logic [H] to logic [L] and the Q output of the D-FF 204 changes to logic [H]. Therefore, the input terminals I 0 , I 1 and I 2 of the decoder 206 become [L], [H] and [L], respectively, and the output of the output terminal Y 0 becomes logic [L].
  • the output of the output terminal Y 1 becomes logic [H], thereby outputting a reset trigger signal to a reset terminal of the first FF circuit 29.
  • the address signal input terminals A 0 and A 1 of the memory 201 become logic [L] and [H], respectively, this time the second re-sync. pattern detection starting time is read from address "2" of the memory 201 and is output to the comparator 202.
  • the third detection signal d 2 is output from the comparator 202. Therefore, the Q output of the D-FF 203 again becomes logic [H] and the Q output of the D-FF 204 is maintained at the logic [H].
  • the input terminal I 0 , I 1 and I 2 of the decoder 206 become [H], [H] and [L], respectively, and the output of the decoder 206 enables only output terminal Y 2 to be at logic [H].
  • the set trigger signal is thus output to the set terminal S of the fifth FF circuit 35.
  • the second re-sync. pattern detection ending time is read out from memory address 3 of the memory 201 and is output to comparator 202.
  • the count value of the reference clock counter 27 becomes equal to the second re-sync. pattern detection ending time and then the fourth detection signal d 2 is output from the comparator 202. Therefore, the Q output of the D-FFs 203, 204 and 205 are at the logic [L], [L] and [H], respectively, and these logic values are applied to the input terminals I 0 , I 1 and I 2 of the decoder 206. Only the output terminal Y 0 of the decoder 206 becomes logic [H] and the reset trigger signal is output to the reset terminal R of the fifth FF circuit 35.
  • the read address signal input terminals A 0 and A 1 of the memory 201 are again initially set to [L].
  • the first control circuit 28 When the count value of the reference clock counter 27 becomes identical to the pattern detection starting time, the first control circuit 28 outputs the set trigger signal and the first FF circuit 29 outputs the enable signal EN1 (logic [H]) shown in FIG. 7 to the comparator 23. Then, the comparator 23 responds to this enable signal EN1 to detect whether or not the sync. pattern data is included in the data sequentially read out from the optical disc.
  • the timing counter 33 When the comparator 23 detects the sync. pattern data and outputs the sync. signal detection signal SG1 during the enable signal EN1 being output, the timing counter 33 is reset and restarts the counting operation, whereas the second FF circuit 30 is set in the reset state.
  • the reset trigger signal When the count value of reference clock counter 27 reaches the sync. pattern detection time, the reset trigger signal is output from the first control circuit 28,.the enable signal EN1 from the first FF circuit 29 is lost and the detection of the sync. pattern data and the judgment of the result detected by the comparator 23 is finished.
  • the comparator 23 detects the sync. pattern data, thereby to reset second FF circuit 30 and outputs the sync. signal detection signal SG1
  • the set trigger signal is not output from the AND circuit 31 to the third FF circuit 32. Accordingly, the output of the third FF circuit 32 is not inverted and its signal is maintained at the logic [L] level. Consequently, since the signal of logic [L] level maintained by the third FF circuit 32 is input to the AND circuit 41, the comparator 26 is inhibited from detecting the re-sync. pattern data at a detection timing based on the third control circuit 39 (i.e., from the second re-sync. pattern detection starting time to the second re-sync. pattern detection ending time).
  • the second control circuit 34 When the count value of the timing counter 33 reaches the first re-sync. pattern detection starting time, the second control circuit 34 outputs the set trigger signal to the fourth FF circuit 35 which outputs the signal of logic [H] level to the AND circuit 36.
  • the enable signal EN2 is output to the comparator 26 from the AND circuit 36 through the OR circuit 38, and the detection of the re-sync. pattern data is started by the comparator 26.
  • the timing counter 33 When the comparator 26 detects the re-sync. pattern. data and outputs the re-sync. signal detection signal SG2, the timing counter 33 is reset and restarts the count operation as noted earlier.
  • the detection of data in each re-sync. data portion 11c of the data portion 11 in this sector by comparator 26 is continued from now on on the basis of enable signal EN2 controlled by the second control circuit 34.
  • the sync. signal detection signal SG1 is output from the comparator 23.
  • the output of the second FF circuit 30 is not inverted and the second FF circuit 30 is maintained in its set state and the timing counter 33 is not reset.
  • the reset trigger signal is output from the first control circuit 38, the set trigger signal is output to the third FF circuit 32 from the AND circuit 31, the output of the third FF circuit 32 being inverted and the third FF circuit 32 is placed in a set state in which the output signal thereof goes to logic [H] level.
  • the third control circuit 39 outputs the set trigger signal to enable the comparator 26 to start the detection of the re-sync. pattern data. This detection is started earlier than the detection starting time at which the second control circuit 34 starts the detection.
  • a reference timing for reading the re-sync. pattern data is not determined and the timing at which the re-sync. pattern data appears is fluctuates by substantially the same amount as the timing at which the sync. pattern appears and thus the detection of the re-sync. pattern starts at an earlier stage.
  • the re-sync. pattern detection ending time is delayed as compared with the first re-sync. pattern detection ending time in an opposite manner to the second re-sync. pattern detection starting time. Accordingly, even when the detection of the sync. pattern data has failed, and as the re-sync.
  • pattern data starts detection ending time of comparator 26 is more extended forward and backward as compared with the case the sync. pattern data detection is successful.
  • the re-sync. pattern data following the sync. pattern data can be detected with certainty even in the case the timing for reading the following re-sync. pattern data being read out from the record reproduction head cannot be detected.
  • the comparator 26 detects and judges the re-sync. pattern data during this detection time determined by the second re-sync. pattern detection starting time and second re-sync. pattern detection ending time, then the comparator 26 outputs the re-sync. signal detection signal SG2 to the timing counter 33 and also outputs it to the sixth FF circuit 42. Then, the timing counter 33 is reset and the timing counter 33 starts the count operation for detecting the succeeding re-sync. pattern data in this sector.
  • the reset trigger signal is output from the third control circuit 39, the output of the third FF circuit 32 is inverted (from logic [H] level to logic [L] level).
  • the following detection of the succeeding re-sync. pattern data is performed on the basis of the second control circuit 34 from the third control circuit 39.
  • the output of sixth FF circuit 42 is not reversed and signal RDNG designating a failure of the data read is output from AND circuit 45 in synchronization with a reset trigger signal output from the third control circuit 39 to the fifth FF circuit.
  • the detection time of the succeeding re-sync. pattern data is determined so as to fall in a narrow range on the basis of the detection of the sync. pattern data so that, when the detection of the first sync. pattern data has failed, the succeeding re-sync. pattern data cannot be detected and the data of the sector cannot be read out.
  • the detection time of the re-sync. pattern data is extended forward and backward, even if the detection of the first sync. pattern data has failed, the re-sync. pattern data can be positively captured and detected, and data following the detected re-sync. pattern data can be read out. Further, data of one divided unit between the sync.
  • the error correcting circuit produces a CRC for the interleaved data and ECC based on the data, the control word and the above CRC in units of an interleave, thereby adding CRC and ECC to data for recording.
  • the succeeding re-sync. signal can be detected positively so that, although the first divided unit of data is dropped out, the data following the first re-sync. signal can be reliably read out. This reduces the data read error rate, thus achieving a great advantage for a method and apparatus for reading a synchronizing signal from a recording medium.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Signal Processing For Digital Recording And Reproducing (AREA)
US07/642,575 1990-01-17 1991-01-17 Method for reading a synchronizing signal from a record medium and an apparatus thereof Expired - Fee Related US5604723A (en)

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JP2-007843 1990-01-17
JP2007843A JP2998161B2 (ja) 1990-01-17 1990-01-17 記録媒体の同期信号読取方法及び装置

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US5796690A (en) * 1994-04-26 1998-08-18 Nec Corporation Disc controller with improved data sync and re-sync mark detection
US5848218A (en) * 1995-03-31 1998-12-08 Samsung Electronics Co., Ltd. Adaptive sync protection method in digital reproduction systems and apparatus therefor
US20030219236A1 (en) * 2002-05-22 2003-11-27 Satoshi Noro Decoder
US6711225B1 (en) * 2000-05-26 2004-03-23 Marvell International, Ltd. Method and apparatus for synchronization of a bit stream for long latency data detection
US20040156282A1 (en) * 2003-02-06 2004-08-12 Satoshi Noro Decoder
US20060098544A1 (en) * 2004-11-10 2006-05-11 Victor Company Of Japan, Ltd. Method of detecting sync signals

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KR100287493B1 (ko) * 1993-02-12 2001-04-16 이데이 노부유끼 디스크구동장치
US6557113B1 (en) * 1999-10-26 2003-04-29 Iomega Corporation Synchronization recovery technique for storage media

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Also Published As

Publication number Publication date
JPH03211690A (ja) 1991-09-17
DE69125299D1 (de) 1997-04-30
DE69125299T2 (de) 1997-07-10
EP0438355A1 (en) 1991-07-24
JP2998161B2 (ja) 2000-01-11
EP0438355B1 (en) 1997-03-26

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